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UNITED sfrATas. rArENr oFrroE.

WM. HALL, or CHELSEA, MAssAoHUsE'rrs.

LGK FOCR.` SAEES, BANK-VAULTS, &c.

Specificaton of Letters Patent No. 8,221; datedAugust 17, 1843.

To all (witam/it may colncem:

lowing descriptiomtaken in connection with the accompanying drawingsthereof, forms a full and eXact specification of the same;

Figure 1,` of` the drawings above mentioned, represents the interior ofa lock having its levers arranged ;to operatelon my improved method, thebolt of the said lock being in this `View thrown entirely back or withinthe lock case. Fig. 2 is a View of the position of the several partsofthe interior of the lock when the bolt is` thrown completely forwardbythe key. a i a A, Figs. 1, and 2, denotes the lock case, which isconstructed in the ordinarvmanner and .has a slidingbolt B, suitablyadapted to it. The said bolt being `combined with a series O, ofleversor sliding plates, the particular arrangement of which I shall nowproceed to describe. The number oflevers composing the series may Varyat pleasure. Each of them has two Vertical andparallel slots a, Z),formed through it, near its center, or in any other convenient partthereof; and which are connected together by a transverse and somewhatcurVed and inclined slot c. This slot operates upon a stud d, which isinserted firmly and immovably in the lock case and projects throughitheseries of levers as seen in Figs. 1, and 2. Inlfront of and somewhatbelow the slot a, each lever or sliding plate has a third Vertical slote, cut through it, from any suitable part of which a horizontal slot f,extends forward entirely through it to the front edge of the plate-asseen in the drawings. The rear side of the Vertical slot e, has suitableangular notches g, g, g, cut inI it, similar notches h, h, h, being alsoformed in the front edge of each of the levers-a short distance directlyabove and below the front extremity of the horizontalislot f. A studprojecting from the bolt, operates within the vVertical and horizontalslots, e, lEach lever or slidiug plate of the series C, is sustained inposition at its top part by means of a cylindrcal stud or pin 7a, whichprojects from the lock case and passes through a Vertical and elongatedslot Z, cut through the upper part of the leVer. This slot is to be ofsuificient length to admit of the free and requisitefvertical y jmoi'fements ofzthe levers and the top and Be it knownthat I, WILLIAMHALL, of: Chelsea, inthe county .ofSufolk and State of Massachusetts,have invcnted a certain` new and useful` Improvement in Locks for'Safes, Bank-Vaults, &c., and that thefolbottom` parts of it should eachter'minate or be cut out in a semicircle of the diameter of the stud Ju,the same being as represented in the drawings. Besides the above, everylever` has a horizontal4 or other suitable shoulder m, formed in therear of, or near the slot Z, upon which (shoulder) the extremlty of alever a, rests and is forced thereuppn by means of a bent springho. Asmall washer, or thin circular plate, p, (see Figs. 1, 2,8, thelatterfigure representing the washeras detached) is placed upon the center pin76, and between every two of the faces of the `levers in appositionwitheach other, its `object being to keep the surfaces of the levers a shortdistance apart.` The said surfaces are also kept fromlcontact near thelowenend of the levers, `by means of a lthin elongated strip or plate gofmetal similarly interspersed between them andlsustained; in a restsagainst a fiXed Stud, t, inserted in andV projecting from the lock case.The lower edge of the rear part of the bolt rests and moves upon thestud t. The stud which projects from the bolt and operates in the slotse, should have angular teeth formed in its rear side to correspond withthe angui lar notches g, g, h, 77,, before mentioned. A side view of thekey to this lock is represented in Fig. 4:. It has two series of bits o,

o, '0, of unequal lengths adapted to it, there being the same number ofmovable bits inserted in the keyat one time-as there are lever plates inthe lock. The stationary bit w, of the key is for the purpose ofthrowing the bolt back and forth. The movable bits of each series areformed of Various lengths and are fitted to the key, and confinedtherein by a screw in the usual manner. The bits of one series are forthe purpose of elevating the levers or sliding plates to the requisiteheights to permit the passage of the `stud through the horizontal slotf, while those of the other series are to elevate the levers to suchheights as to bring the slots c, into the position to allow the stud (Z,to pass through them, or in other words to elevate the slots o,`

of levers to the height of the stud (Z, in order to permit such leversas may be so actuated to be thrown forward by the bolt as seen in F ig.2. Each of the levers being properly numbered and corresponding numbersor designating marks being engraved or stamped on their several bits ofeach series of bits, it will be seen that, if ten lever plates are usedin the lock and we make up the key with five bits of each series five ofthe levers will be thrown forward by the bolt while the other' five willsimply be raised and clepressed vertically. Thus it will be seen thatfor any particular number of levers or sliding plates we are enabled bythe above arrangement of their slots, to employ double the number ofhits in elfecting the Changes of the key, that we can as these leversare usually arranged and operated. This multiplication of the bits in atwo fold proportion so increases the number of changes of the key, as torender this an increased security against the attempt of picklocks.Again by having a set of bits separate from those in the key-should animpression of the key be taken-and a set of bits made corresponding tothose in the key, a removal of two or three of the bits thereof, and asubstitution of the same number of the other series of bits, will soefiiectually change the key as to prevent the opening of the lock by theduplicate bits made from the impression. In this i consists the greatsecurity of this lock or its advantages over others. As soon as thecross slot c, of either of the levers has passed over the fixed Stud ofthe bolt case, or in other words, the bolt passed through the said slot,when the levers are thrown forward, or so as to bring the said stud intothe vertical slot Z), each of the said levers will drop downward untilthe top of the slot comes into contact with, or rests upon the top ofthe stud. This being accomplished, it will be impossible to retract thebolt while the said levers so remain. They must be elevated by theirrespective bits of the second series to the requisite height before thebolt will carry the lever back to a Vertical position.

Having thus explained my' improvement, I shall claim- Constructing thelevers or sliding plates with additibnal slots ai, Z), 0, playing upon afixed stud projecting through them and inserted in the lock case andOperating or throwing forward (with the bolt) one or more of the saidsliding plates, by a corresponding number of bits of a secondary orsupplementary series of bits affixed to the key and in connection withthose by which the remaining levers are elevated and actuacted as setforth, the whole being arranged substantially in the manner and for thepurpose as above specified.

In testimony that the above is a correct specification of my saidimprovement I have hereto set my signature this twenty Seventh day ofJune in the year, A. D. 1843.

TWM. HALL.

Vitnesses:

R. H. EDDY, JOHN NOBLE.

